Taming The SRU - December 07, 2015 - By Timothy Morphy
"SO, WHAT CONSTITUTES A “POSITIVE” TAP WHEN EVALUATING FOR SUBARACHNOID HEMORRHAGE?
Traditional teaching is that a positive tap is Xanthochromia or blood in the CSF...
WHAT ABOUT COMBINING XANTHOCHROMIA AND RBC COUNTS?
This was recently studied by Perry et al. They found that a lack of xanthochromia and a RBC count less than 2000 x 106/L excluded the diagnosis of aneurysmal SAH. This rule was 100% sensitive. You can see the numbers from their study below:
While this is promising, there is still more work to be done on this subject.
SO WHAT AM I SUPPOSED TO DO?
Know the evidence, and make a decision for yourself on what constitutes a “positive” LP for SAH.
http://www.tamingthesru.com/blog/diagnostics/csf-evaluation-in-sah